Meteorites of Martian origin found on Earth demonstrate that material has been
exchanged between planets in the Solar System. These rocks are thought
to have been ejected from their home planets
by giant impact events of asteroids, and possible transfer of living microbes on such
ejecta to other planets
has been discussed in the literature as the panspermia hypothesis
[1]}.
Rocks ejected from Earth or Mars eventually fall onto planets after
\(\sim 10^{6-7}\)  yrs stay in orbits, but 10–20% of these are ejected
from the Solar System by interaction with the giant planets [2]}, [3]}.
This implies the possibility of interstellar transfer of living organisms,
but previous studies found
negligibly small success probabilities
[3]}, [5]}, [6]}, [7]}.
Interstellar panspermia is limited not only by large distances to nearby stars,
but also by the survival time of organisms in space
(\(\sim 10^{5-7}\)  yrs, [6]}, [9]})
and the minimum rock size (\(\gtrsim 10\)  kg, [6]}, [7]}) to protect
microbes during the journey.
